'It echoes a tense stand-off in 2001 between U.S. and Chinese military forces after a U.S. spy plane made an emergency landing on Hainan after a collision with a Chinese fighter jet. China released 24 crew after a U.S. apology.'

BEIJING, March 10 (Reuters) - China said a U.S. naval vessel was conducting illegal surveying off its southern island of Hainan, a Hong Kong television website reported on Tuesday, after the Pentagon said Chinese ships had harassed the vessel in international waters.

The United States on Monday urged China to observe international maritime rules after the Pentagon said five Chinese ships, including a naval vessel, harassed a U.S. Navy ship in international waters.

The Chinese vessels "shadowed and aggressively manoeuvred in dangerously close proximity" to the USNS Impeccable, an unarmed ocean surveillance vessel, on Sunday, with one ship coming within 25 feet (7.6 metres), a U.S. Defense Department statement said.

An unnamed spokesman from the Chinese embassy in Washington denied the Chinese ships had violated maritime rules, and said U.S. ships had been conducting illegal surveying, the website of Hong Kong-based Phoenix Television (news.ifeng.com) reported.

"The U.S. claim about operating in high seas is out of step with the facts," the report quoted the spokesman as saying. "The U.S. navy vessel concerned has been consistently conducting illegal surveying in China's special economic zone," the station quoted the spokesman as saying.

"China believes this contravenes international laws of the sea and China's relevant laws."

Chinese authorities had "repeatedly used diplomatic channels to demand that the U.S. side cease unlawful activities in China's special economic zone", the report added.

The Chinese Foreign Ministry was unavailable for comment.

U.S. defence officials said the incident followed days of increasingly aggressive Chinese conduct in the area, including fly-bys of two U.S. Navy ships by Chinese maritime surveillance planes.

It echoes a tense stand-off in 2001 between U.S. and Chinese military forces after a U.S. spy plane made an emergency landing on Hainan after a collision with a Chinese fighter jet. China released 24 crew after a U.S. apology.

The Impeccable is one of five ocean surveillance ships that serve with the U.S. 7th Fleet, which is based Yokosuka, Japan. The ships use low-frequency sound to search for undersea threats including submarines, a U.S. military official said.

Hainan Island is the site of a Chinese naval base that houses ballistic missile submarines, according to independent analysts.

A U.S. Defense Department spokesman said the Chinese vessels had surrounded the Impeccable, waving Chinese flags and telling the U.S. ship to leave.

The Pentagon also described accounts of half a dozen other incidents dating back to March 4, in which the Impeccable and its sister vessel, USNS Victorious, were subjected to aggressive behaviour.

Oil jumped more than 3 percent to $47 a barrel amid the naval incident between China and the United States and as dealers pondered the possibility of deeper production cuts by OPEC.